Jack guide for loom shedding mechanism



Dec. 24, 1940.

v. H. JENNINGS JACK GUIDE FOR LOOM SHEDDING MECHANISM Filed June 24, 1939 RE E4 m y. e mm n t6 r J 0 mu m n A 1m c mn Patented Dec. 24, 1940 UNITED STATES 4 men onion FOR LOOM SHEDDING MECHANISM Victor H. Jennings Worcester, Mass, assi gnor to Crompton & Knowles Loom Works, Worcester,

Mass, acorpcration of Massachusetts Application June 24, 1939, Serial No. 281,044

7 Claims. (Cl. 139-6'?) can be distributed among the jacks with no This invention relates to improvements in shedding mechanisms for looms andait is the general object of the inventionto provide improved guide means for the harness liftingiacks 5 of such mechanisms. 1

Fancy looms employ a relatively large number of harness frames which can be lifted independently of each other by means of harness jacks contained in a shedding mechanism.-- One 19 form of such'mechanism which has gone into extensive use is the so-called dobbyv in which oppositely reciprocating knives engage pattern controlled hooks to lift the harness jacks .or

allow them to remain down in accordance with pattern demands. .The jacks are connected to the harness frames by cords or the like which are trained over' sheaves carried bythe loom arches. The knives move angularly during their lifting strokes and the changing angular relation between the knives and thejacks tends to cause vibration of those parts ofthe jacks which are attached to the harness cords. If this vibration becomes excessive the jacks interfere with each other as do also the connecting cords and the latter are pulled in a direction slightly oblique with respect to the 'planesin which the sheaves turn with theresult thati'the cords tend to move laterally off the sheaves.

It has been proposed heretoforeto restrain this vibration by means of short guides floated on supports adjacent to the lowerends of the jacks. These guides as previously used have been too far from the cord attaching ends of the jacks to restrain vibration of the latter effec- 5 tively at high loom speeds. ,They have also vibrated with the jacks and were incapable of exerting sufiicient restraining force on the jacks.

It is an important object of my present invention to provide a jack guide at each sideof the set of jacks which shall be in lateralalignment with parts of the jacks closely; adjacent to the harness cord connectors and to provide means for holding the guides in fixed position with-respect to the loom frame. By thus'holding the guides I prevent them from vibrating and am also able to hold the jacks in'alignmentwith their respective sheaves. j

The previously usedguides have been free to move toward the center of the set of harness jacks and a part of the total space available fordistribution among I the ,jacks has been shared by the guides, with the result that the guides themselves have by their loose mounting contributed to the accumulation. of clearance spaces. It is another objectofmy-presentinvention to make unnecessary; the; provision of clearances for the guides by fastening the latter rigidly in position and holdingthem against mo- M tion toward the center of vthesetof jacks. In

this way the total space allowablefor clearances necessity for providing clearances for the guides. In the practice of my invention I have found that the guides can' be effectively held in position by supporting connections from the loom arches and that as a matter of practical operation it is unnecessary to hold the lower parts of the guides positively against lateral motion. I do-not wish, however, to belimited-to a construction in which there is but one positive mounting for each jack guide.

It is a further object of my invention to provide supporting means for the jack guides so constructed that pressures exerted outwardly from the center of the set of jacks will act to force the guide supporting stands against the part of the loom frame on which they are mounted, such for instance as the loom arches. In connection with the aforesaid stands itis a further object of my present invention to provide them with guide supporting screws adjustable in the stands in a direction laterally of the set of jacks so that the latter can be aligned with their respective sheaves. I

With these and other objects in View which will appear as the description proceeds,tmyin vention resides in the combination and arrangement of parts hereinafter described and set forth.

In the accompanying drawing, wherein a convenient embodiment of my invention is set forth Fig. 1 is a front view of a dobby having my invention applied thereto,

Fig. 2 is an end elevation of the front part of the dobby taken from the center of the loom and in the direction of arrow 2, Fig. 1, the arch being in section, and t 1 Fig. 3 is a diagrammatic plan view of the structure shown in Fig. 1 on a reduced 'sca'le. Referring to the drawing, I have shown a form of dobby having harness jacks and reciprocating knives to move the jacks. While I have shown. my invention in connection with this particulartype of dobby I do not wish my invention to be limited to such a form of harness mechanism, since the invention is applicable to a series of harness jacks without particular re- .gard to the type of actuator which moves them. The loom frame III has mounted thereon a pair of dobby sides ll between which extends a rocker shaft I2. This shaft carries front and rear actuator arms one of which is shown at l3 and the arms and shaft are rockedback and forth by mechanism not shown but wellunderstood. Connectors l4 impart the rocking motion of the levers to the top and bottomknives l5 and I6, respectively, so that the latter reciprocate in vertically spaced horizontal planes in opposite directions. It is a characteristic of the particular dobby set forth herein that the ed thereto.

rear ends of the knives move through a greater distance than do their front ends so that the rear harnesses may be lifted higher than the front harnesses to form the shed necessary for the passage of the shuttle.

The front and back loom arches 20 and 2!, respectively, have their left ends secured to the corresponding doddy sides and the arches may be T-shaped in vertical section as indicated in Fig.

2. There is located between these arches a set J of harness jacks, each jack comprising an upright lever 22 the upper end of which maybe notched as at 23 for attachment by means of a jack eye 24 to harness cord 25. The cords pass over sheaves one set of which is shown at S in Fig. 3, and these sheaves are mounted for free rotation on a shaft 26 supported by the arches. A supporting pin 39 extends between and is connected to the lower parts of the dobby sides and forms a pivotal support for the lower ends of the jacks 22. Each jack has a central substantially horizontal arm 3| to which is pivoted a dobby back lever 32 connected at its upper end lower ends to hooks 33 and 34, respectively. These hooks are controlled as to vertical position by means of pattern mechanism not shown and cooperate with the previously described knives. As shown in Fig. 1 the dobby back levers are vertical and have both of their ends resting against cross girts 35 extending between the dobby sides. This is the condition which the dobby back levers and the jacks connected to them assume when the warp is to be down. When the warp is to be raised either the top or the bottom of the selected dobby back lever 32 is moved to the left as viewed in Fig. 1 to rock the associated jack in a counter-clockwise direction around pin 30. The resultant motion to the left of the harness cords 25 lifts the harness frame 36, see Fig. 3, connect- The lower right hand part of each jack is slotted as at 31 to receive a guide rod 38 extending between the dobby sides. This slot is concentric with pin 30 and assists in placing the jacks in correct position.

It is believed that the operation of the dobby is sufficiently understood from the description already given, but I may state that the motion of the dobby jacks in a lifting direction, or to the left as viewed in Figs. 1 and 3 away from the sheaves S, is accompanied by a certain amount of lateral vibration in a direction transverse of the arches. In the form of dobby shown this vibration may be due to the slight spreading of the hooks as the knife to which they are connected moves from a position oblique with respect to the dobby sides to a position substantially perpendicular to them. The strain of lifting the harness frames together with the fact that the jacks are necessarily of this section is in all likelihood a contributing factor to the vibration.

The eyes 24 are purposely made narrow to avoid interference during rocking of adjacent levers in opposite directions, but any lateral vibration on the part of the jacks, particularly the upper ends thereof, is likely to cause engagement between adjacent eyes with resultant interference with the proper motions of the harness frames. When vibration occurs during the return motion of a jack in a right hand direction as viewed in Fig. 1 to lower the associated harness there is a tendency for the harness cord to slide off its sheave.

My present invention aims to provide means which will prevent the aforesaid vibration of the harness sheaves and in carrying my invention into effect I provide a guide at each side of the set of harness jacks. Since these guides may be similar or in fact identical I will describe but one of them.

51 on the guide may also engage a similar run 58 on the-adjacent jack. 1

A placing stop screw 60 is threaded into the dobby side II and presses against the run 55 of the guide as shown in Fig. 2, and the second screw 6| similar to screw 60 is also threaded through the lower part of the dobby side to engage a part of the foot 5|. These screws 60 and 6| limit'motion of the lower part of the guide 56 toward the adjacent dobby side.

The upper part of my improved guide is held positively with respect to the loom frame and in carrying this feature of my invention into effect I secure a stand 65 to each arch by means of a bolt 66 as shown in Fig. 2. The stand has a foot 67 held by the bolt to the vertical web of the arch and located between the latter and the guide 50. An upright arm 68 forming part of the stand has passing loosely therethrough a horizontal positioning screw 69 which is threaded into the guide 50. Nuts 10 on screw 69 lie on opposite sides of arm 68 and afford means for adjusting the screw and therefore the jack guide relatively to the stand. A lock nut II also on screw 69 is turned tightly against the guide to hold the screw from turning.

The upper end of each harness jack has an arcuate arm 15 concentric with pin 36 and thicker than the web of the jack. The top of the jack guide is also formed with an arcuate rib 16 concentric with pin, 36 and extending along and in engagement with the arcuate arm of the adjacent jack. Rib I6 is preferably wider than the web of the jack guide.

In dobbies equipped with my invention I have noticed a marked lessening of vibration of the jacks, particularly their upper ends. The jacks move back and forth in their planes of motion more smoothly than in dobbies not provided with the guides, andthere is little or no interference between adjacent jack eyes.

By means of the positioning screws 69 each guide can be moved to a position which will afford a minimum amount of clearance between the adjacent jacks but at the same time prevent any substantial lateral vibration. In this way I am enabled to determine positively the width of the space to be occupied by the jacks and by reason of the adjustable features of the positioning screws 69 I can align the jacks with the sheaves of the set S, as willbe apparent from Fig. 3. Since the upper ends of the guides are held positively the space measured laterally of the arches which can be used for clearance can be used solely for the jacks since the guides are fixed and need no clearance.

While I have shown the screws 66 and 6| as merely pressing against the lower ends of the guides, I do not wish necessarily to be limited to this construction, inasmuch as a construction similar to the positioning screw 69 and its stand can if desired be substituted for the screws ti] and 6|. I find, however, that the chief tendency to vibration of the jacks exists at their upper ends where they have contact with the harness eyes, and a single means forpositively holding that part of the jack guide which is adjacent to the upper ends of the jacks acts satisfactorily to check the vibration. The fact that the stands 65 are on the arches and relatively high in the harness actuating system is believed to contribute to the effectiveness of the guides to prevent lateral vibration.

From the foregoing it will be seen that I have provided a simple form of guide for harness sheaves located between the arches and adjacent parts of the jacks and effective to overcome the tendency of the jacks to vibrate objectionably in a transverse direction. It will also be seen that the feet 61 of the stands 65 are so placed that any outward force originating in the center of the set of jacks and transmitted through the positioning screws 69 tends to hold the stands against their supporting arches. It will also be seen that the total clearance space to be distributed among the jacks is located between adjacent faces of the guides and that this available space need not include any provision for lateral vibration of the guides. Although the upper part of the guides only are fastened positively, I find nevertheless in practice that the guide as a whole throughout its height is resistant to vibration.

Having thus described my invention it will be seen that changes and modifications may be made therein by those skilled in the art without departing from the spirit and scope of the invention and I do not wish to be limited to the details herein disclosed, but what I claim is:

1. In a loom having a frame, a set of flat harness lifting jacks arranged side by side, a series of harness cord sheaves supported by the frame arranged side by side, there being a sheave to be aligned with each jack, means to move the jacks toward and from the sheaves through a given angle, a rib on each jack to engage similar ribs of adjacent jacks throughout motion of the jacks through said angle, two guides for the jacks, one located at each end of the set, each guide to engage the rib of the adjacent jack throughout movement of the latter through said given angle, and means to position and hold each guide positively in fixed position with respect to the frame and locate said guides so that the jacks between them will be aligned with their corresponding sheaves.

2. In a loom having a frame, a set of fiat harness lifting jacks arranged side by side, a series of harness cord sheaves supported by the frame arranged side by side, there being a sheave to be aligned with each jack, means to move the jacks toward and from the sheaves'through a given angle, a rib on each jack to engage similar ribs of adjacent jacks throughout motion of the jacks through said angle, a jack guide at each end of the set, a stand fixed to the frame for each jack guide, and threaded means fixed with respect to each stand and threaded into the corresponding jack guide to hold the latter in adjusted fixed position with respect to the frame, said guides determining the location of the set of jacks to keep the latter aligned with their corresponding sheaves.

3. In a loom having a frame, a set of flatharness lifting jacks arranged side by side, a series of harness cord sheaves supported by the frame arranged side by side, there being a sheave to be aligned with each jack, means to move the jacks toward and from the sheaves through a given angle, a rib on each jack to engage similar ribs of adjacent jacks throughout motion of the jacks through said angle, a jack guide at each end of the set, a stand fixed to the frame for each jack guide, a screw passing through each stand and threaded into the corresponding jack guide, and means'to hold the screw in adjusted longitudinal position with respect to the corresponding stand, the stands and screws held thereby holding the jack guides in fixed adjusted position laterally of the direction of motion of the jacks to locate the latter in alignment with their corresponding sheaves. 1

4. In a loom having a frame and warp harnesses, a set of harness lifting jacks arranged side by side, a shaft fixed to the frame on which the jacks are pivoted, means to move the jacks in planes transverse of the shaft through a given angle to effect harness lifting, each jack having a notched upper end and a guide rib adjacent to the notched end, a jack guide at each end of the set of jacks having the lower end thereof supported on the shaft, a stand fixed to the loom frame at each side of the set, and means positively to connect each stand to the corresponding jack guide, whereby each guide is supported with respect to the frame at two spaced points and has the upper end thereof positively positioned with respect to the frame to determine the location of the jacks.

5. In a loom having harness frames, spaced arches forming part of the loom frame, a series of harness cord sheaves supported by the arches, a set of harness jacks movable toward and from the sheaves in planes between the arches, a jack guide between each arch and the adjacent end of the set of jacks, and means fixed to each arch and connected to the adjacent jack guide to hold the latter in fixed position transversely of the arches. v

6. In a loom having harness frames, a pair of spaced loom arches, a series of harness cord sheaves supported by the arches, a set of harness jacks movable toward and from the sheaves in planes between the arches, a jack guide between each arch and the adjacent jack of the set, a r

stand secured to each arch between the latter and the adjacent jack guide, and means to fasten each stand to the adjacent jack guide to hold the latter in fixed position relatively to the adjacent arch.

7. In a loom having harness frames, a pair of spaced loom arches, a series of harness cord sheaves supported by the arches, a set of harness jacks movable toward and from the sheaves in planes between the arches, a jack guide between each arch and the adjacent jack of the set, a stand for each arch having a foot between the arch therefor and the adjacent jack guide, means to hold the foot in fixed position on the arch corresponding thereto, and means carried by the stand and adjustable therein transversely of the arch and connected to each jack guide to hold the latter against lateral motion with respect to the adjacent arch, whereby a force acting in a direction from the center of the set of jacks toward one of the arches tends to force the foot of the stand on said arch toward the latter.

VICTOR H. JENNINGS. 

